Fix idempotency issues in build_essential on the mac
Fix idempotency issues in build_essential on the mac

2 issues this solves:

- On some systems the Command Line Tools aren't showing up in the install history plist we're parsing. This means we attempt to install the tools each time chef runs, which takes a LONG time even on a top of the line mac. It was suggested in mac admins slack to just use xcode-select -p which lists the command line tools path or exits 2 if not installed.

- When the :upgrade action is used we were parsing out the software update list twice for no reason, which made it take even longer.

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>

mattray/chef,tas50/chef-1,mattray/chef,MsysTechnologiesllc/chef,tas50/chef-1,chef/chef,nvwls/chef,nvwls/chef,chef/chef,chef/chef,gene1wood/chef,mwrock/chef,mattray/chef,nvwls/chef,MsysTechnologiesllc/chef,nvwls/chef,mwrock/chef,chef/chef,mattray/chef,mwrock/chef,MsysTechnologiesllc/chef,tas50/chef-1,MsysTechnologiesllc/chef,mattray/chef,mwrock/chef,tas50/chef-1,gene1wood/chef,gene1wood/chef,nvwls/chef,nvwls/chef,gene1wood/chef